A general strike in Greece on Friday halted trains and ferries, grounded flights and disrupted public services as thousands of workers walked off the job on the second anniversary of Greece’s worst-ever train disaster.

The 24-hour walkout, called by Greece’s two main labor unions, was the latest in a series of public protests over a dragging judicial investigation into the crash, in which 57 people were killed.

There is still lingering anger in the country over the government’s failure to put any of its politicians under scrutiny over the loss of life.

Here is what to know about the strike and the enduring anger over the accident.

What did the strike entail?

Rallies took place in Athens and across Greece, with protesters calling for those at fault in the crash to be punished and for rail safety to be improved.

The strike involved public- and private-sector workers. A police official estimated that the Athens protest attracted at least 180,000 people, the largest demonstration in the Greek capital in years.

All commercial flights to and from Greek airports were grounded, and no ferries or trains were running. Limited public transportation was operating in Athens to allow demonstrators to get to the rally.